JadeGreen17
Chimeric Spirit
This thread is going to be a guide to space travel and space combat in RPs. I see a lot of people on the "Guides" thread talking about things they are knowledgeable in.
This will not be a thread about the actual physics of real space travel, because many settings tend not to utilize space mechanics that abide by known science. If you are interested in learning more about how real spaceflight works I would strongly recommend watching some educational Youtube videos, reading a high school physics textbook or playing Kerbal Space Program (#notsponsored). I might touch on topics relating to real science and spaceflight but I will not be diving into them, because frankly I would find that to be a waste of my time and yours. Mine because there are other people that can explain these topics much more comprehensively and coherently than myself, and there is already tons of information about how this stuff works, and your time because a majority of the most successful and popular tend to not utilize these scientific at length. This thread will focus mostly on space warfare, but will cover some general tropes of space travel and exploration.
I need to emphasize strongly that ignoring scientific accuracy in space travel and science fiction is not necessary. Star wars, Star Trek, Halo, Mass Effect, Warhammer (especially) all break one or more known scientific principles or utilize technologies (or plain magic) that changes how space behaves. Yet these are all amongst the most successful and recognizable science fiction IPs in the world. This is because many of the liberties taken with science lend themselves to much more interesting stories and exciting conflicts. This isn't to say that hard science fiction can't lend itself to interesting stories, but often the challenges associated with living in a universe that completely obeys realistic science can shape major conflicts in a story and prohibit other story arcs or events from occurring. It is my firm personal believe that anyone interested in science fiction should be able to appreciate both rock solid and scientifically accurate science fiction and more fantastical space opera and fantasy, even if they prefer one end of the spectrum over the other. (I am mostly saying this because I wish to bypass the tired and petty argument about which sub-genre is actually better.)
There are a number of writers, game designers and angry people on the internet trying to tell people exactly what a "realistic" spacefairing society and what realistic space warfare would be like. But the truth is they are all wrong. Because we truthfully don't know what space warfare will be like because our technology has not reached that point yet. We don't know which technologies will develop and which ones will prove to be impossible. When constructing any setting it isn't really all that important to construct your space travel mechanics to work within the bounds of known science (though that can be nice), so long as your space travel mechanics are internally consistent and do not take the reader out of the experience/story by presenting inconsistent rules, you are free to do whatever you want. (within reason, of course.)
Also for the purpose of this guide, I'm going to drop a mention to a lot of popular science fiction ips (star wars in particular) here and there but probably not overview specific fleets or ships or mechanics from any such setting, though it will probably be plainly obvious to people which science fiction settings I know a lot about and which I don't after awhile. I'm more interested in educating people on the general tropes and ideas within the genre. As such this guide isn't meant to specifically teach you about IPs, but more so educate folks and get the pot stirring for any writing or RPs you might want to do within a science fiction setting. (Because there are people (and wikis) more knowledgeable than me who can do that.) If there is a particular subject you want me to talk about let me know.
A pretty easy way to determine if you are in a hard sci fi or soft sci fi setting, or somewhere in-between, is to look for the following things:
This will not be a thread about the actual physics of real space travel, because many settings tend not to utilize space mechanics that abide by known science. If you are interested in learning more about how real spaceflight works I would strongly recommend watching some educational Youtube videos, reading a high school physics textbook or playing Kerbal Space Program (#notsponsored). I might touch on topics relating to real science and spaceflight but I will not be diving into them, because frankly I would find that to be a waste of my time and yours. Mine because there are other people that can explain these topics much more comprehensively and coherently than myself, and there is already tons of information about how this stuff works, and your time because a majority of the most successful and popular tend to not utilize these scientific at length. This thread will focus mostly on space warfare, but will cover some general tropes of space travel and exploration.
I need to emphasize strongly that ignoring scientific accuracy in space travel and science fiction is not necessary. Star wars, Star Trek, Halo, Mass Effect, Warhammer (especially) all break one or more known scientific principles or utilize technologies (or plain magic) that changes how space behaves. Yet these are all amongst the most successful and recognizable science fiction IPs in the world. This is because many of the liberties taken with science lend themselves to much more interesting stories and exciting conflicts. This isn't to say that hard science fiction can't lend itself to interesting stories, but often the challenges associated with living in a universe that completely obeys realistic science can shape major conflicts in a story and prohibit other story arcs or events from occurring. It is my firm personal believe that anyone interested in science fiction should be able to appreciate both rock solid and scientifically accurate science fiction and more fantastical space opera and fantasy, even if they prefer one end of the spectrum over the other. (I am mostly saying this because I wish to bypass the tired and petty argument about which sub-genre is actually better.)
There are a number of writers, game designers and angry people on the internet trying to tell people exactly what a "realistic" spacefairing society and what realistic space warfare would be like. But the truth is they are all wrong. Because we truthfully don't know what space warfare will be like because our technology has not reached that point yet. We don't know which technologies will develop and which ones will prove to be impossible. When constructing any setting it isn't really all that important to construct your space travel mechanics to work within the bounds of known science (though that can be nice), so long as your space travel mechanics are internally consistent and do not take the reader out of the experience/story by presenting inconsistent rules, you are free to do whatever you want. (within reason, of course.)
Also for the purpose of this guide, I'm going to drop a mention to a lot of popular science fiction ips (star wars in particular) here and there but probably not overview specific fleets or ships or mechanics from any such setting, though it will probably be plainly obvious to people which science fiction settings I know a lot about and which I don't after awhile. I'm more interested in educating people on the general tropes and ideas within the genre. As such this guide isn't meant to specifically teach you about IPs, but more so educate folks and get the pot stirring for any writing or RPs you might want to do within a science fiction setting. (Because there are people (and wikis) more knowledgeable than me who can do that.) If there is a particular subject you want me to talk about let me know.
A pretty easy way to determine if you are in a hard sci fi or soft sci fi setting, or somewhere in-between, is to look for the following things:
| Trope/Technology | In Hard Scifi | In Soft Scifi | Notes |
| Faster than light travel | Does not exist | Usually Exists | Faster than light travel is more or less essential in any setting where travel between star systems occurs; in order for events to occur on anything approaching realistic timelines. Even if your characters posess immortality, it can take them many years to reach even the closest star systems without FTL. If your setting takes place within a single solar system, then FTL is not necessary given sufficiently powerful engines. (See The Expanse and Epstien Drives) |
| Energy Shields | Does not exist | Usually Exists | Energy shields vary wildly in behaviors, practicality and functionality between settings. They exist in softer science fiction quite a lot to allow spaceship fights to be bombastic and more drawn out, and allow ships and their crew an opportunity to make a few mistakes without having their ship torn apart in the opening moments of a fight. |
| Ship Combat Ranges | Ships Fight outside of visual range (Usually) | Ships Fight inside of visual range almost always. | Mostly a trope associated with visual media. It is far more exciting and engaging to see starships in sight of one another blasting chunks out of one another, rather than shooting at radar blips with missiles. Jamming of long range targeting of missiles or maneuvering to avoid shots are the typical reasons that are used in a setting to explain why ships have to fight at closer ranges. |
| Artificial Gravity | Exists, but only in the form of continuously accelerating a ship with decks opposite the direction of thrust, or spinning a ship or space station such that centrifugal force generates gravity. Ships often have ring or cylinder shaped structures on them which can be seen to rotate. | Ships have artificial gravity through generators. Ships almost always have flat decks oriented perpendicular to the direction of movement/the main engines with an obvious "top" and "bottom", a bridge tower, etc. | Artificial Gravity is basically a necessity for any Movie or TV show wanting to take place onboard a space station or space ship, as otherwise they would have to be shot with the crew floating around at all times (a lot of wire-work.) There is a practical reason for artifical gravity, that being that muscles and bones would deteriorate without a steady supply of gravity. |
| Thruster Placement | Ships will typically have thrusters in every direction to allow them to move or translate in every direction. | Ships will only have thrusters on the rear and somehow be able to maneuver in every direction. | I'm going to talk about this. |
| Fluid Space/Real Space | -If you push on something it will keep going. -If a ship fires its engines one way it will keep moving that way, faster and faster for ever. Ships can achieve very high relative velocities and theoretically zip by (or crash into) one another at several kilometers per second. -Ships make use of orbital mechanics in their flight. They can preform gravity slingshots around planets, be caught in gravity wells, etc. | -Ships tend to have a maximum speed. -The gravity wells of planets and celestial bodies tend to go largely ignored. -Ships have "wings" and are known to tilt and bank when turning like airplanes. -Ships, when flying in formation or fighting will typically align their definitive "top" sides and only very rarely are seen "sideways" or "upside down" -Ships tend to fight on a mostly two dimensional plane. | Fluid space is a concept popularized by major science fiction franchises in where space is treated something like an ocean where planets are "islands". More importantly it tends to treat space as though there is a medium like air or water present that requires ships to be "aerodynamic" to some degree, and to turn and behave in a particular manner. |
Types of ships:
This seems to be a concept popularized by Star Wars, to utilize naval monikers to determine a type of ship and what job it should do within a fleet, but there are a couple other ones that utilize other monkiers too. I've seen varying (often contradictory) opinions from different sources about what these words should really mean and what they should say about what a ship's job is within a fleet. Many of the naval terms commonly used for these ship types are quite antiquated, leading to a (sometimes needlessly intense) debate about what these terms should mean, when even actual real-life navies due to bureaucracy and fleet shenanigans with juggling different ships often don't keep these terms straight any better than scifi writers.
I will say a point that I think is important to reiterate throughout this post. That being that it isn't necessarily important that something is consistent with real life, moreso than it is consistent within a setting. So if you want to have your own idea behind what these words mean, or have an in-universe reason for why a ship's classification doesn't line up with what it should be then go for it. If you just want to not use the naval classification and call your different ship types Zorgs, Zergs and Blargs, that's fine too. So long as it's clear what role each ship type would play within a fleet.
Also I will say not every single science fiction ship you can think of will fit perfectly into this classification system.
And one final note. Just please. Whatever you do. Don't name your ship like this. Or this.
This seems to be a concept popularized by Star Wars, to utilize naval monikers to determine a type of ship and what job it should do within a fleet, but there are a couple other ones that utilize other monkiers too. I've seen varying (often contradictory) opinions from different sources about what these words should really mean and what they should say about what a ship's job is within a fleet. Many of the naval terms commonly used for these ship types are quite antiquated, leading to a (sometimes needlessly intense) debate about what these terms should mean, when even actual real-life navies due to bureaucracy and fleet shenanigans with juggling different ships often don't keep these terms straight any better than scifi writers.
I will say a point that I think is important to reiterate throughout this post. That being that it isn't necessarily important that something is consistent with real life, moreso than it is consistent within a setting. So if you want to have your own idea behind what these words mean, or have an in-universe reason for why a ship's classification doesn't line up with what it should be then go for it. If you just want to not use the naval classification and call your different ship types Zorgs, Zergs and Blargs, that's fine too. So long as it's clear what role each ship type would play within a fleet.
Also I will say not every single science fiction ship you can think of will fit perfectly into this classification system.
And one final note. Just please. Whatever you do. Don't name your ship like this. Or this.
| Ship Type | Notes |
| Strike Craft | A Strike Craft usually refers to any type of craft that is generally small with less than three or four crew members. If there's space to get up and walk around inside of a ship then it's generally not what I would consider a strike craft. These are usually the ships that are treated more like "airplanes" than "boats" following along with the whole "space is an ocean" analogy. These ships are usually carried or launched from hangar bays aboard larger ships but in settings with FTL they may also possess their own FTL mechanism. |
| Interceptor | An interceptor is usually the smallest type of strike craft. As their name implies their job is to intercept incoming enemies, normally enemy fighters or bombers. Usually interceptors are small, fast and are lightly armored. |
| Fighter | Fighters are the defacto strike-craft of any fleet or faction. They are usually well rounded between speed, firepower and defensive countermeasures and are larger than interceptors. |
| Bomber | Bombers are usually big, slow to turn and maneuver. They can range from fairly well armored to flying explosive barrels. They usually carry heavy ordinance in the form of missiles or bombs meant to attack enemy capital ships or ground based installations, but are vulnerable to other fighters. If any strike craft within a particular faction is going to have more than one crewmember, its usually the bomber that gets this treatment, and its usually because that bomber has a secondary gun turret or requires a bombadier/gunner. |
| Dropship | Dropships are ships meant to transport troops and sometimes ground vehicles to and from a planet's surface. These ships can range from flying tinder boxes to fairly capable warships in their own right, and usually have weapons to clear a landing zone before they drop off troops or vehicles, and usually have the capability to fly in both space and atmosphere and do so even if their mothership cannot land. Though often, with scifi ships measuring a kilometer in more or in length, finding a suitable location to land could be difficult, or specific weapons systems could shoot down larger ships. |
| Shuttle | Shuttles are usually like dropships (sometimes the words are used interchangeably) However shuttles don't often have weapons, are more likely to have some type of FTL. Given they are unarmed they are usually used to transport high ranking personel. |
| Gunship | A gunship is a strike craft that carries a lot of weapons. But unlike a bomber these are usually weapons meant for attacking other targets be they enemy ships or targets on the surface of a planet. Some IPs or factions will inconsistently treat gunships both as the more maneuverable strike craft type of ship and the more "boat-like" lumber ship; but of a small size. |
| Capital Ship | (Boy are there some heated arguments about this one) I tend to classify a capital ship, at least in a military fleet as more or less anything big enough to have multiple decks, people walking around in it, or crews in it for long periods of time, launches fighters, or has its own hangar bays. Still there are some pedantic people looking to have nerd rage arguments that will say otherwise; some way that as a "capital" ship it should be the biggest or most important ship in a fleet or a ship that is the "capital" of the fleet, just like the capital of a country. Though I, and most science fiction for that matter tend to use it as a blanket term for any ship that meets the above listed criteria, and obeys the more "boat" like behavior. Though "capital" can also be thought of in the sense of business capital. (If you're a carpenter, your capital would be your tools, your drill and saw. Things you would need to buy but wouldn't use up.) With the connotation being that any scifi military might view a strike craft or some infantry as an anticipated loss but could not lose or willingly expend a capital ship. |
| Corvette | Corvettes are the smallest capital ships in terms of size and usually have a focus on speed rather than firepower or armor. |
| Frigate | Frigates are medium sized capital ships and usually have fairly balanced statistics. In most settings/IPs frigates tend to be fairly easy to build/purchase/commission and are used to bulk out fleets but not be a match for larger ships unless they have a large numbers advantage over the enemy, and are usually designed specifically to work as part of a larger fleet. |
| Destroyer | Scifi tends to misuse this term a lot, and second to the term of "capital ship" this is the one that seems to generate the most heated arguments. Many people just call a destroyer "something bigger than a frigate but smaller than a cruiser." To me you might as well just have a heavy frigate or a light cruiser. I tend to use the term "destroyer" in terms of a ship meant to punch above its weight class, as there is such a thing as a Tank Destroyer. These vehicles were popular in the WWII era and were typically lightly armored platforms mounting a huge gun, meant to destroy tanks. But were lightly armored and therefore couldn't compete with tanks directly. As such I tend to think of destroyers as glass cannon ships (usually operating in that size range of a large frigate or small cruiser, but not always). Mostly just as ships that can punch larger ships but can't take that same punishment in return. |
| Cruiser | A cruiser is the standard ship of any scifi fleet. These ships are usually well balanced but unlike frigates are big enough to hold up to most threats on their own, travel out away from a main fleet on their own, and should work well on their own or as part of a larger fleet. In settings/factions that have strike craft, cruisers usually carry a few of them, but not as many as a dedicated carrier. The focus of these ships is often versatility and depending upon what weapons systems are available within the setting they'll often have at least a couple of each. |
| Battleship | Battleships is quite an old term. It's not used in modern navy because it specifically refers to old-school naval warfare in where the biggest ship with the biggest guns that could shoot the farthest and the thickest armor would usually be the winner. Battleships are usually much larger than the average cruiser or frigate and factions generally don't have very many of them as they will be, within the setting, very difficult and resource intensive to commission and build. They are usually (but not always) lacking in maneuverability but more than making up for it in heavy weaponry and shielding. |
| Battlecruiser | This actually belongs somewhere between a battleship and a cruiser, and often falls there in the general sliding scale of ship sizes. Often a battleship that sacrifices some armor and weapons to be a bit more maneuverable or have a bit more hangar space or, heck, just be designed in a more economical and practical mindset such that they aren't exceedingly rare. In some settings battle cruisers are actually the biggest ship types. |
| Dreadnought | Dreadnought is another term bound to infuriate people as not only horribly out of date, it is the name of a particular ship. (Dreadnought = Dread- not = Fear Not). Typically the way the term is used in scifi is to declare a ship that carries some type of superweapon, or to just have a battleship bigger than a battleship. (There are quite a few terms jockeying for the position of "we describe the biggest, baddest ship within a space fleet) |
| Carrier | This one should be self-evident. This ship is meant to carry other military assets into battle. In settings or factions with fighters/strike craft the carrier is usually their home base, and if cruiser carry some fighters, carriers will carry far, far more. If the carrier itself cannot land on a planet it will deploy dropships to do so. Carriers can have weapons but due to them turning over a lot of interior space to troop and vehicle storage they tend not to be as well armed or armored as a similarly sized warship. |
| Supercarrier | It's a carrier. But really big. |
| Mothership | Synonymous with a Supercarrier. Though the term mothership is applied almost exclusively to non-human factions of |
| Battle Carrier | This one should also be self evident. This is a carrier, but one that also turns over a considerable amount of tonnage to offensive and defensive capabilities. These are a great or a terrible idea depending upon who you ask. Great because they can punch through enemy orbital blockades and land troops in one go. Terrible because by making a ship thats okay as both a carrier and a warship, it ends up being excellent at neither, or losing out in some other area. |
| Titan | A Titan is usually the biggest, baddest ship in a fleet or a flagship, and usually refers to a ship that has everything a Battleship or Dreadnought has while also having everything a carrier has. In essence it's a battle carrier on roids. I think that this term was popularized by the game Eve online, a property that I must confess I am not particularly familiar with. |
| Interdictor | I don't know if this concept is exclusive to star wars, or originated from star wars but Star Wars was certainly what popularized it. This ship carries a method or technology by which it can prevent other ships from entering light speed to escape. For reasons usually involving technobabble or in-setting bearucratic meddling, these are seperate ships (often with mediocre defensive capabilities), rather than have this technology built into standard cruisers. |
Faster than Light Travel:
This will be a list of the various methods of faster than light travel present in scifi. Faster than light travel is an essential element of science fiction as it allows for ships to make interstellar voyages, when under known physics these voyages would take at minimum several years (assuming a ship could reach something like 50-90% the speed of light. Also there's a lot of really funky ways people have achieved their FTL across various science fiction stories, but most of the time they end up being a variation or combination of one of the below.
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The Other Dimension:
There is some other dimension which a ship travels into. This dimension either acts as a sort of subspace. (Like the nether in minecraft, where in traveling one block in the nether travels you 8 blocks in the Overworld). In essence a ship could travel 1 kilometer in this dimension and then exit, having traveled 8 kilometers, or something to that effect. In reality, in order to achieve the travel times utilized in sci fi this dimension would have to compress space by a factor of about a million, at least. This would make things quite difficult as if a ship was off by just a centimeter in the subspace dimension it could be off by thousands of light years when it exits. (Used by Star Wars, Halo, Warhammer 40k (but its full of demons) )
View attachment 601242
This is a Diagram from my original science fiction setting, in where the other dimension actually exists as a continuous gradient. The deeper you go the greater the distance between points is contracted and ships with more advanced subspace drives can go deeper into subspace and therefore move faster. This also allows for precision long jumps with the right navigational equipment as you can travel in lower subspace for travel between star systems (distances often measured in light-years), and then drop into higher subspace for more precise approaches; such to make sure you don't fly past the planet you were aiming for (distances measured in light-hours or light minutes) If you travel to the bottom of subspace you actually end up "looping around" into a state of superposition and being ejected back into the universe at a random point. But because you could be anywhere and nowhere simultaneously you could theoretically end up billions of light years from where you started; this ends up being a key plot point for a side story about a ship with an experimental drive accidentally getting stranded very far from their home civilization.
The Warp Drive:
The warp drive bends space such that space behind the ship expands and the space in front of the ship contracts. Technically the ship is sitting still, the space around it is being bent. (Used by Star Trek)
The Wormhole Drive:
The wormhole drive doesn't just bend space it breaks it. If one imagines space as a 2d plane; a sheet of paper that can be folded and then have two distant points of the sheet connected, and then cross over, that is how a wormhole drive works.
The Neagtive Mass Drive: I don't remember where I heard of this one but the basic logic behind it is that something with mass is constrained to moving below light speed, unless it has infinite energy. A photon, which has no mass can move at light speed. Therefore something with negative mass should be able to move ABOVE light speed. The physics of this are dubious. Though one method is to, by some mechanism, convert the ship into tachyons or some particle that can move faster than light and then somehow convert the ship back to normal matter upon arriving at your destination.
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There are also two other concepts that are commonly seen in FTL.
FTL relays or gates: In this instance the Faster than Light travel is not executed by the ship, at least not in part. In this instance it is required that there be some form of gate or relay to conduct faster than light travel. The exact shenanigans involved can vary from setting to setting from a portal or wormhole style structures at key points in the solar system, to simply a navigational beacon where a ship otherwise has a high chance of getting lost, to a catalyst required to activate a separate drive onboard the ship. Sometimes the gates are the result of a precursor civilization, and in other instances they are able to be constructed by the civilizations presently active within the setting (albeit often with a high resource cost). In settings where these are necessary for faster than light travel they are often pivotal to military conflicts as they serve as a choke point for fleets entering and leaving, and threatening to destroy them, cutting off worlds temporarily or permanently.
FTL does not work on/near planets: I don't think that this always applies, but in many settings its common for faster than light travel to be disrupted by planets or gravitational fields. This means (In theory at least) that in any setting with FTL that is disrupted by gravity fields and settings with the potential to generate artificial gravity through means other than spin gravity or acceleration gravity, it is possible to create an interdictor ship. Though this frequently does not happen because artificial gravity is often a difficult technology within settings and producing a field large and powerful enough to interdict ships over any useful range would require orders of magnitude more power than it would to simply produce the field inside a ship and at an intensity that is comfortable for people. An alternative explanation is that FTL is somewhat imprecise and there is the possibility that a ship could collide with a planet, hence ships are required to jump well away from a planet and make their approach at sub-light speed.
This will be a list of the various methods of faster than light travel present in scifi. Faster than light travel is an essential element of science fiction as it allows for ships to make interstellar voyages, when under known physics these voyages would take at minimum several years (assuming a ship could reach something like 50-90% the speed of light. Also there's a lot of really funky ways people have achieved their FTL across various science fiction stories, but most of the time they end up being a variation or combination of one of the below.
-+-
The Other Dimension:
There is some other dimension which a ship travels into. This dimension either acts as a sort of subspace. (Like the nether in minecraft, where in traveling one block in the nether travels you 8 blocks in the Overworld). In essence a ship could travel 1 kilometer in this dimension and then exit, having traveled 8 kilometers, or something to that effect. In reality, in order to achieve the travel times utilized in sci fi this dimension would have to compress space by a factor of about a million, at least. This would make things quite difficult as if a ship was off by just a centimeter in the subspace dimension it could be off by thousands of light years when it exits. (Used by Star Wars, Halo, Warhammer 40k (but its full of demons) )
View attachment 601242
This is a Diagram from my original science fiction setting, in where the other dimension actually exists as a continuous gradient. The deeper you go the greater the distance between points is contracted and ships with more advanced subspace drives can go deeper into subspace and therefore move faster. This also allows for precision long jumps with the right navigational equipment as you can travel in lower subspace for travel between star systems (distances often measured in light-years), and then drop into higher subspace for more precise approaches; such to make sure you don't fly past the planet you were aiming for (distances measured in light-hours or light minutes) If you travel to the bottom of subspace you actually end up "looping around" into a state of superposition and being ejected back into the universe at a random point. But because you could be anywhere and nowhere simultaneously you could theoretically end up billions of light years from where you started; this ends up being a key plot point for a side story about a ship with an experimental drive accidentally getting stranded very far from their home civilization.
The Warp Drive:
The warp drive bends space such that space behind the ship expands and the space in front of the ship contracts. Technically the ship is sitting still, the space around it is being bent. (Used by Star Trek)
The Wormhole Drive:
The wormhole drive doesn't just bend space it breaks it. If one imagines space as a 2d plane; a sheet of paper that can be folded and then have two distant points of the sheet connected, and then cross over, that is how a wormhole drive works.
The Neagtive Mass Drive: I don't remember where I heard of this one but the basic logic behind it is that something with mass is constrained to moving below light speed, unless it has infinite energy. A photon, which has no mass can move at light speed. Therefore something with negative mass should be able to move ABOVE light speed. The physics of this are dubious. Though one method is to, by some mechanism, convert the ship into tachyons or some particle that can move faster than light and then somehow convert the ship back to normal matter upon arriving at your destination.
-+-
There are also two other concepts that are commonly seen in FTL.
FTL relays or gates: In this instance the Faster than Light travel is not executed by the ship, at least not in part. In this instance it is required that there be some form of gate or relay to conduct faster than light travel. The exact shenanigans involved can vary from setting to setting from a portal or wormhole style structures at key points in the solar system, to simply a navigational beacon where a ship otherwise has a high chance of getting lost, to a catalyst required to activate a separate drive onboard the ship. Sometimes the gates are the result of a precursor civilization, and in other instances they are able to be constructed by the civilizations presently active within the setting (albeit often with a high resource cost). In settings where these are necessary for faster than light travel they are often pivotal to military conflicts as they serve as a choke point for fleets entering and leaving, and threatening to destroy them, cutting off worlds temporarily or permanently.
FTL does not work on/near planets: I don't think that this always applies, but in many settings its common for faster than light travel to be disrupted by planets or gravitational fields. This means (In theory at least) that in any setting with FTL that is disrupted by gravity fields and settings with the potential to generate artificial gravity through means other than spin gravity or acceleration gravity, it is possible to create an interdictor ship. Though this frequently does not happen because artificial gravity is often a difficult technology within settings and producing a field large and powerful enough to interdict ships over any useful range would require orders of magnitude more power than it would to simply produce the field inside a ship and at an intensity that is comfortable for people. An alternative explanation is that FTL is somewhat imprecise and there is the possibility that a ship could collide with a planet, hence ships are required to jump well away from a planet and make their approach at sub-light speed.
Normally in science fiction ships make a very clear distinction between sub light travel and faster than light travel. Slower than light travel is typically used for flight between planets, moons or space stations using what we would consider conventional rocket engines, at least in the sense of "every action has an equal and opposite reaction". That's all a rocket engine is, really, just something that throws hot gas out one way and makes the ship move the other way. In this instance the ship is moving normally through real space and not preforming any of the shenanigans that it would be during travel in faster than light travel. As such people can see it, shoot at it and what have you. I'm going to cover a wide range of sub light propulsion methods, beginning with real and moving to the more theoretical or downright fictional methods.
Chemical rockets: Chemical rockets are what are used today, by people like Nasa and SpaceX. Essentially they work by burning combustable propellants (commonly liquid oxygen with liquid hydrogen, liquid methane or liquid RP1 (which is essentially highly refined petroleum), and then focusing the exhaust stream out the engine nozzle (that bell shaped thingy). In science fiction these rockets typically work as only historical artifacts, relics of low tech civilizations. In truth they aren't much use in lower realism science fiction settings due to other options often being far better and much more commonplace. The main drawbacks would be fuel boiloff (the supercooled fuels, if not actively cooled, will begin to boil off and leak out of the tanks). These fuels also take up quite a lot of space (most of your ship will be made of fuel tanks) and yet, due to the low energy involved with chemical propulsion you won't actually get very much out of that fuel. If real-world rockets are anything to go by you won't even be able to lift off from an earth-sized planet without using staged boosters. So if you want to fly from planet-to-planet, chemical rockets are probably not the way to go. There are some variations on this, such as monopropellant rockets (which, as the name implies) only have a single propellant. As such you're essentially just venting a pressurized gas into space, and rockets which use hypergolic fuels. Hypergolic fuels combust without an ignition source when injected into the combustion chamber of a rocket, meaning the rocket can be re-ignited multiple times.
Ion Drive: This seems to be by far the most popular drive in science fiction. An ion drive works by ionizing the propellant causing it to shoot out the back at insane speeds. Ion drives actually do exist on a few satellites and space probes. Real life ion drives tend to suffer from painfully low thrust, though they are very efficient. This low thrust means they are useless for lifting off from a planet, since they would never be able to generate more thrust than was needed to counteract gravity. (though a lot of lower-realism science fiction tends to bypass this issue with more advanced power generation, materials or general technology.) Though Ion drives can be made efficient enough to potentially tour multiple planets without refueling as is shown in science fiction. Of course, in real life, with the problem of gravity and acceleration, one would not be able to actually land on any of the planets they visited.
Atomic Rocket: In this instance, instead of a chemical reaction, a small nuclear fission reactor would be placed inside of an engine and the heat generated by it would cause propellant passed through it to shoot out the back. (It is important to note that if these engines are working properly, the exhaust it not radioactive. Though in many instances of their use in hard science fiction, they are often radioactive themselves due to the radiation given off by the reactors. This ultimately comes down to the amount of shielding around the reactor and how well maintained the engine is. Atomic rockets have been tested on the ground but never seen action in space. These engines can have better efficiency than chemical engines (you should probably be able to lift off from an earth-sized planet into low orbit without running out of fuel) but you'll hardly be able to hop from planet to planet without refueling.
Orion Drive (the other kind of atomic rocket): Some proof-of-concept tests have been done of this type of propulsion, but never any full scale tests. The Orion Drive is probably the most metal type of spacecraft propulsion around, consisting of a big armored plate and a ton of atomic bombs. The concept essentially states that you launch nukes near your own spaceship and use the blasts to propel you where you want to go. (with a big, radiation shielding, shock-absorbing plate between you and the nuke, of course) This has obvious environmental concerns since you'll be scattering radioactive dust wherever you go, and the large amount of nuclear devices you need will probably drive up the cost of the craft, or at the very least its fuel. In hard scifi settings, I always felt this would make for a great warship since one end of your ship is a big armored slab that has a hole in the middle through which you can use to shoot out nukes.
Fusion Drive: Fusion is a more energetic nuclear reaction than fission, and has the added benefit of having a fuel that is the most common stuff in the universe (hydrogen.) A fusion drive is essentially an ongoing nuclear fusion reaction which is blasting out the back of the ship (probably contained by electromagnetic or artificially created gravitational fields to prevent it from melting the ship's engine. A fusion drive would, in theory, be radioactive, at least when the engine is firing. But it would not have the potential to leak its reactor contents or have the fallout of dozens of atomic bombs. If the drive was to malfunction, the reaction would mostly likely, simply stop. Normally in any scifi setting, hard or soft, with a decent understanding of nuclear fusion will use these types of drives. A theoretical version of this drive called the Bussard ramjet exists which actually involved a jet-like intake which sucks in the very thin free floating hydrogen present in space and uses it as fuel. In theory a ship reliant partially or fully on such a drive could have a functional reason for having air intakes like a jet fighter.
Magnetic Thruster: This is basically half of a particle accelerator/supercollider. You electromagnetically accelerate a particle or stream of particles to near light speed and then shoot it out the back of the ship. If your particles can attain speeds near light speed, almost nothing will beat the fuel efficiency of such a drive.
Antimatter Thruster: I plan to talk more about antimatter in a future. But when antimatter touches normal matter the two will annihilate one another into pure energy. There aren't a lot of substances, fictional or nonfictional which beat this kind of energy density of fuel. The downside is of course, the antimatter component of your fuel needs to be contained within magnetic fields, and if there should be a containment failure and the antimatter touch the inside of the ship (made of regular matter) the result will be a very. big. explosion.
The Gravity Thruster/Reaction-less Thruster: Probably the undisputed kind of science fiction thruster is the use of gravity manipulation technology to propel a ship. This is defiantly the least scientifically grounded type of engine, but arguably the most useful as one does not have to concern themselves with fuel or reaction mass, so long as the ship maintains power to the drive. The physics and mechanics of such systems vary based upon setting between the ship pulling or pushing on celestial bodies with tractor beams, to pulling and pushing off of nothing, or inducing a gravity field on itself, but tend to agree upon that this method of propulsion lends itself to no visible thrusters on the outside of the ship.
But what about steering?
Because we are primates used to living on a flat planet where there is a very clear up and down, and because a lot of science fiction takes cues from the "space is an ocean" trope where spacecraft are equivalent to sea fairing ships, spacecraft tend to have a designated up and down with ships generally being long, with their engines on the rear, and a designated "upward" direction of the ship perpendicular to the longest axis and the direction of forward thrust. Which begs the question of how exactly a spacecraft can turn or slow down (unless someone is using a fluid space model), or land when its engines are facing in the wrong direction. There are depressingly few IPs (both hard and soft) which actually look to address this problem.
There are really four possible solutions to this problem, which I have chosen to order from ones that I believe are the most viable to ones which I believe are the least viable. Though arguably the most viable method would be to hybridize more than one of these proposed methods. Of course don't let my personal biases get in the way, if you wish to construct your setting in one way or another, then that's fine with me.
Solution 1: Gyroscopes: The ship has internal gyroscopes or reaction wheels which allow it to rotate, while its engines are fixed to firing out the rear. This seems like a poor choice because if a ship needs to make a minor course correction or slow down, it needs to turn itself a large amount.
Solution 2: Thrust Vectoring: In this instance a ship can be turned by turning the engines. By some mechanism aiming the engines or their exhaust streams, one can induce torque on the ship, causing it to turn. There are quite a lot of medium sized ships and drop-ships that make use of an osprey-style configuration, with engines that can angle backwards or down if a ship is landing.
Solution 3: Gravity Manipulation: In this instance the forward thrust is provided by the main engines in addition to some device which allows the ship to move and rotate in other directions without the need for visible thrusters, presumably through the use of gravity manipulation. This will allow a ship to hover above a planet's surface.
Solution 4: Maneuvering Thrusters: This is arguably the best idea, though depending upon the established mechanics of spacecraft construction within a setting the reasons for it. Depressingly few softer science fiction settings make use of thrusters anywhere on a ship besides the rear. Engines might be expensive, or vulnerable hardware which could be prone to being damaged in battles. Or perhaps the thrust stream would interfere with the ship's shields (or vice versa).
Decks: Ship Style or Skyscraper Style?
Most scifi ships tend to have the decks arranged perpendicular to the axis of thrust. Though this allows the ship to fly horizontally in atmosphere like a flying naval vessel (again, we are primates used to living with a very clear up and down.) that is without artifical gravity, which, if present within a setting could theoretically allow a ship with its decks facing in any orientation to land at any other orientation and be fine, so long as the gravity generation on the ship remained operational. It would be disorienting when one boarded or exited a ship, for sure (and could lead to a calamity if the artificial gravity of a ship went offline while the ship was landed or flying in atmosphere.) Of course in a setting with gravity manipulation, you can actually have your ships' internal decks oriented however you want, so long as the capacity to shape the gravitational fields exists. So in theory there are limitless solutions to this problem including having the ceiling of each deck of the ship be another floor, having a hallway with gravity oriented perpendicular to the decks such that people can walk up and down an 'elevator shaft', and then through a transition hallway which curves like a slide to each primary deck. Though in Hard-Sci-Fi (or any setting without artificial gravity) you are limited to acceleration based gravity (skyscraper style) or any sort of ring or cylinder based spin-gravity.
Skyscraper style has its pros, and I have a personal preference for it. For one, your typical "long" scifi ship can make a landing using its main engines on a planet, and power off the artificial gravity on the interior with no ill effects. Such a ship has far more decks (and in theory more space turned over to elevators or vertical access, a problem present in real skyscrapers). Though I am a personal advocate of this type of ship design in scifi and think it is tragically underutilized in science fiction, this thread is meant to inspire others' creativity when it comes to their world building and not coherse you into liking the same thing I like.
Chemical rockets: Chemical rockets are what are used today, by people like Nasa and SpaceX. Essentially they work by burning combustable propellants (commonly liquid oxygen with liquid hydrogen, liquid methane or liquid RP1 (which is essentially highly refined petroleum), and then focusing the exhaust stream out the engine nozzle (that bell shaped thingy). In science fiction these rockets typically work as only historical artifacts, relics of low tech civilizations. In truth they aren't much use in lower realism science fiction settings due to other options often being far better and much more commonplace. The main drawbacks would be fuel boiloff (the supercooled fuels, if not actively cooled, will begin to boil off and leak out of the tanks). These fuels also take up quite a lot of space (most of your ship will be made of fuel tanks) and yet, due to the low energy involved with chemical propulsion you won't actually get very much out of that fuel. If real-world rockets are anything to go by you won't even be able to lift off from an earth-sized planet without using staged boosters. So if you want to fly from planet-to-planet, chemical rockets are probably not the way to go. There are some variations on this, such as monopropellant rockets (which, as the name implies) only have a single propellant. As such you're essentially just venting a pressurized gas into space, and rockets which use hypergolic fuels. Hypergolic fuels combust without an ignition source when injected into the combustion chamber of a rocket, meaning the rocket can be re-ignited multiple times.
Ion Drive: This seems to be by far the most popular drive in science fiction. An ion drive works by ionizing the propellant causing it to shoot out the back at insane speeds. Ion drives actually do exist on a few satellites and space probes. Real life ion drives tend to suffer from painfully low thrust, though they are very efficient. This low thrust means they are useless for lifting off from a planet, since they would never be able to generate more thrust than was needed to counteract gravity. (though a lot of lower-realism science fiction tends to bypass this issue with more advanced power generation, materials or general technology.) Though Ion drives can be made efficient enough to potentially tour multiple planets without refueling as is shown in science fiction. Of course, in real life, with the problem of gravity and acceleration, one would not be able to actually land on any of the planets they visited.
Atomic Rocket: In this instance, instead of a chemical reaction, a small nuclear fission reactor would be placed inside of an engine and the heat generated by it would cause propellant passed through it to shoot out the back. (It is important to note that if these engines are working properly, the exhaust it not radioactive. Though in many instances of their use in hard science fiction, they are often radioactive themselves due to the radiation given off by the reactors. This ultimately comes down to the amount of shielding around the reactor and how well maintained the engine is. Atomic rockets have been tested on the ground but never seen action in space. These engines can have better efficiency than chemical engines (you should probably be able to lift off from an earth-sized planet into low orbit without running out of fuel) but you'll hardly be able to hop from planet to planet without refueling.
Orion Drive (the other kind of atomic rocket): Some proof-of-concept tests have been done of this type of propulsion, but never any full scale tests. The Orion Drive is probably the most metal type of spacecraft propulsion around, consisting of a big armored plate and a ton of atomic bombs. The concept essentially states that you launch nukes near your own spaceship and use the blasts to propel you where you want to go. (with a big, radiation shielding, shock-absorbing plate between you and the nuke, of course) This has obvious environmental concerns since you'll be scattering radioactive dust wherever you go, and the large amount of nuclear devices you need will probably drive up the cost of the craft, or at the very least its fuel. In hard scifi settings, I always felt this would make for a great warship since one end of your ship is a big armored slab that has a hole in the middle through which you can use to shoot out nukes.
Fusion Drive: Fusion is a more energetic nuclear reaction than fission, and has the added benefit of having a fuel that is the most common stuff in the universe (hydrogen.) A fusion drive is essentially an ongoing nuclear fusion reaction which is blasting out the back of the ship (probably contained by electromagnetic or artificially created gravitational fields to prevent it from melting the ship's engine. A fusion drive would, in theory, be radioactive, at least when the engine is firing. But it would not have the potential to leak its reactor contents or have the fallout of dozens of atomic bombs. If the drive was to malfunction, the reaction would mostly likely, simply stop. Normally in any scifi setting, hard or soft, with a decent understanding of nuclear fusion will use these types of drives. A theoretical version of this drive called the Bussard ramjet exists which actually involved a jet-like intake which sucks in the very thin free floating hydrogen present in space and uses it as fuel. In theory a ship reliant partially or fully on such a drive could have a functional reason for having air intakes like a jet fighter.
Magnetic Thruster: This is basically half of a particle accelerator/supercollider. You electromagnetically accelerate a particle or stream of particles to near light speed and then shoot it out the back of the ship. If your particles can attain speeds near light speed, almost nothing will beat the fuel efficiency of such a drive.
Antimatter Thruster: I plan to talk more about antimatter in a future. But when antimatter touches normal matter the two will annihilate one another into pure energy. There aren't a lot of substances, fictional or nonfictional which beat this kind of energy density of fuel. The downside is of course, the antimatter component of your fuel needs to be contained within magnetic fields, and if there should be a containment failure and the antimatter touch the inside of the ship (made of regular matter) the result will be a very. big. explosion.
The Gravity Thruster/Reaction-less Thruster: Probably the undisputed kind of science fiction thruster is the use of gravity manipulation technology to propel a ship. This is defiantly the least scientifically grounded type of engine, but arguably the most useful as one does not have to concern themselves with fuel or reaction mass, so long as the ship maintains power to the drive. The physics and mechanics of such systems vary based upon setting between the ship pulling or pushing on celestial bodies with tractor beams, to pulling and pushing off of nothing, or inducing a gravity field on itself, but tend to agree upon that this method of propulsion lends itself to no visible thrusters on the outside of the ship.
But what about steering?
Because we are primates used to living on a flat planet where there is a very clear up and down, and because a lot of science fiction takes cues from the "space is an ocean" trope where spacecraft are equivalent to sea fairing ships, spacecraft tend to have a designated up and down with ships generally being long, with their engines on the rear, and a designated "upward" direction of the ship perpendicular to the longest axis and the direction of forward thrust. Which begs the question of how exactly a spacecraft can turn or slow down (unless someone is using a fluid space model), or land when its engines are facing in the wrong direction. There are depressingly few IPs (both hard and soft) which actually look to address this problem.
There are really four possible solutions to this problem, which I have chosen to order from ones that I believe are the most viable to ones which I believe are the least viable. Though arguably the most viable method would be to hybridize more than one of these proposed methods. Of course don't let my personal biases get in the way, if you wish to construct your setting in one way or another, then that's fine with me.
Solution 1: Gyroscopes: The ship has internal gyroscopes or reaction wheels which allow it to rotate, while its engines are fixed to firing out the rear. This seems like a poor choice because if a ship needs to make a minor course correction or slow down, it needs to turn itself a large amount.
Solution 2: Thrust Vectoring: In this instance a ship can be turned by turning the engines. By some mechanism aiming the engines or their exhaust streams, one can induce torque on the ship, causing it to turn. There are quite a lot of medium sized ships and drop-ships that make use of an osprey-style configuration, with engines that can angle backwards or down if a ship is landing.
Solution 3: Gravity Manipulation: In this instance the forward thrust is provided by the main engines in addition to some device which allows the ship to move and rotate in other directions without the need for visible thrusters, presumably through the use of gravity manipulation. This will allow a ship to hover above a planet's surface.
Solution 4: Maneuvering Thrusters: This is arguably the best idea, though depending upon the established mechanics of spacecraft construction within a setting the reasons for it. Depressingly few softer science fiction settings make use of thrusters anywhere on a ship besides the rear. Engines might be expensive, or vulnerable hardware which could be prone to being damaged in battles. Or perhaps the thrust stream would interfere with the ship's shields (or vice versa).
Decks: Ship Style or Skyscraper Style?
Most scifi ships tend to have the decks arranged perpendicular to the axis of thrust. Though this allows the ship to fly horizontally in atmosphere like a flying naval vessel (again, we are primates used to living with a very clear up and down.) that is without artifical gravity, which, if present within a setting could theoretically allow a ship with its decks facing in any orientation to land at any other orientation and be fine, so long as the gravity generation on the ship remained operational. It would be disorienting when one boarded or exited a ship, for sure (and could lead to a calamity if the artificial gravity of a ship went offline while the ship was landed or flying in atmosphere.) Of course in a setting with gravity manipulation, you can actually have your ships' internal decks oriented however you want, so long as the capacity to shape the gravitational fields exists. So in theory there are limitless solutions to this problem including having the ceiling of each deck of the ship be another floor, having a hallway with gravity oriented perpendicular to the decks such that people can walk up and down an 'elevator shaft', and then through a transition hallway which curves like a slide to each primary deck. Though in Hard-Sci-Fi (or any setting without artificial gravity) you are limited to acceleration based gravity (skyscraper style) or any sort of ring or cylinder based spin-gravity.
Skyscraper style has its pros, and I have a personal preference for it. For one, your typical "long" scifi ship can make a landing using its main engines on a planet, and power off the artificial gravity on the interior with no ill effects. Such a ship has far more decks (and in theory more space turned over to elevators or vertical access, a problem present in real skyscrapers). Though I am a personal advocate of this type of ship design in scifi and think it is tragically underutilized in science fiction, this thread is meant to inspire others' creativity when it comes to their world building and not coherse you into liking the same thing I like.
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